<?php
/**
 * Zend Framework
 * LICENSE
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 * @category Zend
 * @package Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 * @version $Id: Memcached.php 24593 2012-01-05 20:35:02Z matthew $
 */
/**
 *
 * @see Zend_Cache_Backend_Interface
 */
require_once 'Zend/Cache/Backend/ExtendedInterface.php';
/**
 *
 * @see Zend_Cache_Backend
 */
require_once 'Zend/Cache/Backend.php';

/**
 *
 * @package Zend_Cache
 * @subpackage Zend_Cache_Backend
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 */
class Zend_Cache_Backend_Memcached extends Zend_Cache_Backend implements Zend_Cache_Backend_ExtendedInterface {

    /**
     * Default Values
     */
    const DEFAULT_HOST = '127.0.0.1';

    const DEFAULT_PORT = 11211;

    const DEFAULT_PERSISTENT = true;

    const DEFAULT_WEIGHT = 1;

    const DEFAULT_TIMEOUT = 1;

    const DEFAULT_RETRY_INTERVAL = 15;

    const DEFAULT_STATUS = true;

    const DEFAULT_FAILURE_CALLBACK = null;

    /**
     * Log message
     */
    const TAGS_UNSUPPORTED_BY_CLEAN_OF_MEMCACHED_BACKEND = 'Zend_Cache_Backend_Memcached::clean() : tags are unsupported by the Memcached backend';

    const TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND = 'Zend_Cache_Backend_Memcached::save() : tags are unsupported by the Memcached backend';

    /**
     * Available options
     * =====> (array) servers :
     * an array of memcached server ; each memcached server is described by an associative array :
     * 'host' => (string) : the name of the memcached server
     * 'port' => (int) : the port of the memcached server
     * 'persistent' => (bool) : use or not persistent connections to this memcached server
     * 'weight' => (int) : number of buckets to create for this server which in turn control its
     * probability of it being selected. The probability is relative to the total
     * weight of all servers.
     * 'timeout' => (int) : value in seconds which will be used for connecting to the daemon. Think twice
     * before changing the default value of 1 second - you can lose all the
     * advantages of caching if your connection is too slow.
     * 'retry_interval' => (int) : controls how often a failed server will be retried, the default value
     * is 15 seconds. Setting this parameter to -1 disables automatic retry.
     * 'status' => (bool) : controls if the server should be flagged as online.
     * 'failure_callback' => (callback) : Allows the user to specify a callback function to run upon
     * encountering an error. The callback is run before failover
     * is attempted. The function takes two parameters, the hostname
     * and port of the failed server.
     * =====> (boolean) compression :
     * true if you want to use on-the-fly compression
     * =====> (boolean) compatibility :
     * true if you use old memcache server or extension
     * @var array available options
     */
    protected $_options = array('servers' => array(array('host' => self::DEFAULT_HOST, 'port' => self::DEFAULT_PORT, 'persistent' => self::DEFAULT_PERSISTENT, 'weight' => self::DEFAULT_WEIGHT, 'timeout' => self::DEFAULT_TIMEOUT, 'retry_interval' => self::DEFAULT_RETRY_INTERVAL, 'status' => self::DEFAULT_STATUS, 'failure_callback' => self::DEFAULT_FAILURE_CALLBACK)), 'compression' => false, 'compatibility' => false);

    /**
     * Memcache object
     * @var mixed memcache object
     */
    protected $_memcache = null;

    /**
     * Constructor
     * @param array $options associative array of options
     * @throws Zend_Cache_Exception
     * @return void
     */
    public function __construct (array $options = array()) {
        if ( ! extension_loaded ('memcache')) {
            Zend_Cache::throwException ('The memcache extension must be loaded for using this backend !');
        }
        parent::__construct ($options);
        if (isset ($this -> _options['servers'])) {
            $value = $this -> _options['servers'];
            if (isset ($value['host'])) {
                // in this case, $value seems to be a simple associative array (one server only)
                $value = array(0 => $value); // let's transform it into a classical array of associative arrays
            }
            $this -> setOption ('servers', $value);
        }
        $this -> _memcache = new Memcache ();
        foreach ($this -> _options['servers'] as $server) {
            if ( ! array_key_exists ('port', $server)) {
                $server['port'] = self::DEFAULT_PORT;
            }
            if ( ! array_key_exists ('persistent', $server)) {
                $server['persistent'] = self::DEFAULT_PERSISTENT;
            }
            if ( ! array_key_exists ('weight', $server)) {
                $server['weight'] = self::DEFAULT_WEIGHT;
            }
            if ( ! array_key_exists ('timeout', $server)) {
                $server['timeout'] = self::DEFAULT_TIMEOUT;
            }
            if ( ! array_key_exists ('retry_interval', $server)) {
                $server['retry_interval'] = self::DEFAULT_RETRY_INTERVAL;
            }
            if ( ! array_key_exists ('status', $server)) {
                $server['status'] = self::DEFAULT_STATUS;
            }
            if ( ! array_key_exists ('failure_callback', $server)) {
                $server['failure_callback'] = self::DEFAULT_FAILURE_CALLBACK;
            }
            if ($this -> _options['compatibility']) {
                // No status for compatibility mode (#ZF-5887)
                $this -> _memcache -> addServer ($server['host'], $server['port'], $server['persistent'], $server['weight'], $server['timeout'], $server['retry_interval']);
            } else {
                $this -> _memcache -> addServer ($server['host'], $server['port'], $server['persistent'], $server['weight'], $server['timeout'], $server['retry_interval'], $server['status'], $server['failure_callback']);
            }
        }
    }

    /**
     * Test if a cache is available for the given id and (if yes) return it (false else)
     * @param string $id Cache id
     * @param boolean $doNotTestCacheValidity If set to true, the cache validity won't be tested
     * @return string false datas
     */
    public function load ($id, $doNotTestCacheValidity = false) {
        $tmp = $this -> _memcache -> get ($id);
        if (is_array ($tmp) && isset ($tmp[0])) {
            return $tmp[0];
        }
        return false;
    }

    /**
     * Test if a cache is available or not (for the given id)
     * @param string $id Cache id
     * @return mixed false cache is not available) or "last modified" timestamp (int) of the available cache record
     */
    public function test ($id) {
        $tmp = $this -> _memcache -> get ($id);
        if (is_array ($tmp)) {
            return $tmp[1];
        }
        return false;
    }

    /**
     * Save some string datas into a cache record
     * Note : $data is always "string" (serialization is done by the
     * core not by the backend)
     * @param string $data Datas to cache
     * @param string $id Cache id
     * @param array $tags Array of strings, the cache record will be tagged by each string entry
     * @param int $specificLifetime If != false, set a specific lifetime for this cache record (null => infinite lifetime)
     * @return boolean True if no problem
     */
    public function save ($data, $id, $tags = array(), $specificLifetime = false) {
        $lifetime = $this -> getLifetime ($specificLifetime);
        if ($this -> _options['compression']) {
            $flag = MEMCACHE_COMPRESSED;
        } else {
            $flag = 0;
        }
        // ZF-8856: using set because add needs a second request if item already exists
        $result = @$this -> _memcache -> set ($id, array($data, time (), $lifetime), $flag, $lifetime);
        if (count ($tags) > 0) {
            $this -> _log (self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        }
        return $result;
    }

    /**
     * Remove a cache record
     * @param string $id Cache id
     * @return boolean True if no problem
     */
    public function remove ($id) {
        return $this -> _memcache -> delete ($id, 0);
    }

    /**
     * Clean some cache records
     * Available modes are :
     * 'all' (default) => remove all cache entries ($tags is not used)
     * 'old' => unsupported
     * 'matchingTag' => unsupported
     * 'notMatchingTag' => unsupported
     * 'matchingAnyTag' => unsupported
     * @param string $mode Clean mode
     * @param array $tags Array of tags
     * @throws Zend_Cache_Exception
     * @return boolean True if no problem
     */
    public function clean ($mode = Zend_Cache::CLEANING_MODE_ALL, $tags = array()) {
        switch ($mode) {
            case Zend_Cache::CLEANING_MODE_ALL :
                return $this -> _memcache -> flush ();
                break;
            case Zend_Cache::CLEANING_MODE_OLD :
                $this -> _log ("Zend_Cache_Backend_Memcached::clean() : CLEANING_MODE_OLD is unsupported by the Memcached backend");
                break;
            case Zend_Cache::CLEANING_MODE_MATCHING_TAG :
            case Zend_Cache::CLEANING_MODE_NOT_MATCHING_TAG :
            case Zend_Cache::CLEANING_MODE_MATCHING_ANY_TAG :
                $this -> _log (self::TAGS_UNSUPPORTED_BY_CLEAN_OF_MEMCACHED_BACKEND);
                break;
            default :
                Zend_Cache::throwException ('Invalid mode for clean() method');
                break;
        }
    }

    /**
     * Return true if the automatic cleaning is available for the backend
     * @return boolean
     */
    public function isAutomaticCleaningAvailable () {
        return false;
    }

    /**
     * Set the frontend directives
     * @param array $directives Assoc of directives
     * @throws Zend_Cache_Exception
     * @return void
     */
    public function setDirectives ($directives) {
        parent::setDirectives ($directives);
        $lifetime = $this -> getLifetime (false);
        if ($lifetime > 2592000) {
            // #ZF-3490 : For the memcached backend, there is a lifetime limit of 30 days (2592000 seconds)
            $this -> _log ('memcached backend has a limit of 30 days (2592000 seconds) for the lifetime');
        }
        if ($lifetime === null) {
            // #ZF-4614 : we tranform null to zero to get the maximal lifetime
            parent::setDirectives (array('lifetime' => 0));
        }
    }

    /**
     * Return an array of stored cache ids
     * @return array array of stored cache ids (string)
     */
    public function getIds () {
        $this -> _log ("Zend_Cache_Backend_Memcached::save() : getting the list of cache ids is unsupported by the Memcache backend");
        return array();
    }

    /**
     * Return an array of stored tags
     * @return array array of stored tags (string)
     */
    public function getTags () {
        $this -> _log (self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return array();
    }

    /**
     * Return an array of stored cache ids which match given tags
     * In case of multiple tags, a logical AND is made between tags
     * @param array $tags array of tags
     * @return array array of matching cache ids (string)
     */
    public function getIdsMatchingTags ($tags = array()) {
        $this -> _log (self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return array();
    }

    /**
     * Return an array of stored cache ids which don't match given tags
     * In case of multiple tags, a logical OR is made between tags
     * @param array $tags array of tags
     * @return array array of not matching cache ids (string)
     */
    public function getIdsNotMatchingTags ($tags = array()) {
        $this -> _log (self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return array();
    }

    /**
     * Return an array of stored cache ids which match any given tags
     * In case of multiple tags, a logical AND is made between tags
     * @param array $tags array of tags
     * @return array array of any matching cache ids (string)
     */
    public function getIdsMatchingAnyTags ($tags = array()) {
        $this -> _log (self::TAGS_UNSUPPORTED_BY_SAVE_OF_MEMCACHED_BACKEND);
        return array();
    }

    /**
     * Return the filling percentage of the backend storage
     * @throws Zend_Cache_Exception
     * @return int integer between 0 and 100
     */
    public function getFillingPercentage () {
        $mems = $this -> _memcache -> getExtendedStats ();
        $memSize = null;
        $memUsed = null;
        foreach ($mems as $key => $mem) {
            if ($mem === false) {
                $this -> _log ('can\'t get stat from ' . $key);
                continue;
            }
            $eachSize = $mem['limit_maxbytes'];
            $eachUsed = $mem['bytes'];
            if ($eachUsed > $eachSize) {
                $eachUsed = $eachSize;
            }
            $memSize += $eachSize;
            $memUsed += $eachUsed;
        }
        if ($memSize === null || $memUsed === null) {
            Zend_Cache::throwException ('Can\'t get filling percentage');
        }
        return ((int) (100. * ($memUsed / $memSize)));
    }

    /**
     * Return an array of metadatas for the given cache id
     * The array must include these keys :
     * - expire : the expire timestamp
     * - tags : a string array of tags
     * - mtime : timestamp of last modification time
     * @param string $id cache id
     * @return array array of metadatas (false if the cache id is not found)
     */
    public function getMetadatas ($id) {
        $tmp = $this -> _memcache -> get ($id);
        if (is_array ($tmp)) {
            $data = $tmp[0];
            $mtime = $tmp[1];
            if ( ! isset ($tmp[2])) {
                // because this record is only with 1.7 release
                // if old cache records are still there...
                return false;
            }
            $lifetime = $tmp[2];
            return array('expire' => $mtime + $lifetime, 'tags' => array(), 'mtime' => $mtime);
        }
        return false;
    }

    /**
     * Give (if possible) an extra lifetime to the given cache id
     * @param string $id cache id
     * @param int $extraLifetime
     * @return boolean true if ok
     */
    public function touch ($id, $extraLifetime) {
        if ($this -> _options['compression']) {
            $flag = MEMCACHE_COMPRESSED;
        } else {
            $flag = 0;
        }
        $tmp = $this -> _memcache -> get ($id);
        if (is_array ($tmp)) {
            $data = $tmp[0];
            $mtime = $tmp[1];
            if ( ! isset ($tmp[2])) {
                // because this record is only with 1.7 release
                // if old cache records are still there...
                return false;
            }
            $lifetime = $tmp[2];
            $newLifetime = $lifetime - (time () - $mtime) + $extraLifetime;
            if ($newLifetime <= 0) {
                return false;
            }
            // #ZF-5702 : we try replace() first becase set() seems to be slower
            if ( ! ($result = $this -> _memcache -> replace ($id, array($data, time (), $newLifetime), $flag, $newLifetime))) {
                $result = $this -> _memcache -> set ($id, array($data, time (), $newLifetime), $flag, $newLifetime);
            }
            return $result;
        }
        return false;
    }

    /**
     * Return an associative array of capabilities (booleans) of the backend
     * The array must include these keys :
     * - automatic_cleaning (is automating cleaning necessary)
     * - tags (are tags supported)
     * - expired_read (is it possible to read expired cache records
     * (for doNotTestCacheValidity option for example))
     * - priority does the backend deal with priority when saving
     * - infinite_lifetime (is infinite lifetime can work with this backend)
     * - get_list (is it possible to get the list of cache ids and the complete list of tags)
     * @return array associative of with capabilities
     */
    public function getCapabilities () {
        return array('automatic_cleaning' => false, 'tags' => false, 'expired_read' => false, 'priority' => false, 'infinite_lifetime' => false, 'get_list' => false);
    }

}
